It is known, for example, from DE-A-2105638 to form a rotary knob having a plurality of rotational positions in order to adjust the power of a heating device. The power is adjusted merely by means of rotation.
It is also known from U.S. Pat. No. 4,713,502 that a corresponding operating control device with a rotary knob in an OFF position cannot be rotated. From the OFF position, the rotary knob has to be pulled out or pushed in order to be brought into a working position in which it can then be rotated for adjusting the power of a heating device. Solutions of this type, in particular if the rotary knob first of all has to be pressed in so as to be subsequently actuated, have in the meantime become widespread in use. In said working position, a large range of rotation, for example 270°, can then be provided. The range of rotation can be divided into several steps or power levels, or, in the case of an oven selector switch, also into different functions. The angle of rotation range is brought about by a certain angular range around the zero position being omitted from a full circle angle since the rotary knob here can be brought from the working position into the off position and vice versa.